Burke Law Group has 26 employees across eight offices, according to its website.
Gov. Mikie Sherrill blasted ICE and called for accountability after she was turned away, but the head of DHS called it a political stunt.
Demonstrators say agents used pepper spray and batons during the scuffle at Delaney Hall in Newark early Monday morning.
Sen. Andy Kim and Rep. Robert Menendez Jr. visited Delaney Hall on Saturday to support detainees who have begun a hunger strike.
The Trump administration's latest policy of deporting immigrants to "third countries" to which they have no ties is unlawful and must be set aside, a federal judge ruled Wednesday in a case that already reached the nation's highest court.
Department of State has stood behind the practice of third country deportations and defended it as a part of Trump's campaign to end illegal immigration.